Winter bovine dysentery seen more than usual in recent months
Published on Feb. 29, 2020
Completely unrelated to the human strain causing worldwide concern, bovine coronavirus has been affecting the beef and dairy industry for years. This virus is the cause of winter bovine dysentery, which has seemed to pop up in feedlot and cow/calf operations more than usual the last few months.
During Kansas State University’s (KSU) Agriculture Today podcast, KSU State Veterinarian Dr. Gregg Hanzlicek discussed risk factors, treatment and prevention strategies for winter bovine dysentery.
Winter bovine dysentery
“Bovine coronavirus is a baby calf scour causing organism that we now think is also associated with mild respiratory disease,” explains Hanzlicek. “There is a strain of this coronavirus that actually causes adult diarrhea in cows and bulls, typically two to six years of age.”
Hanzlicek notes coronavirus is the cause of winter bovine dysentery, which more commonly affects dairy cattle, although they have seen it pop up in some cow/calf and feedlot operations recently.
“We have had three cases come through our diagnostics lab in the last few months which is a little strange,” he states.
Hanzlicek notes the clinical sign of winter bovine dysentery is a sudden, severe case of adult diarrhea.
“A producer will walk out one day and his cows are fine, but when he walks out the next day, 50 to 100 percent of his herd will have blackish-green diarrhea,” he explains. “Some of these animals won’t actually be passing fecal material, just blood clots, which can be really disturbing.”
He further explains the disease comes on suddenly and spreads through a herd very rapidly.
“We think there is a fecal-oral transmission, but we also know it can be spread via aerosol, or breathing,” he says.
As far as animal behavior goes, Hanzlicek notes changes will be mild.
“They do have diarrhea, so they will go off feed,” he explains. “There might be some mild nasal discharge. Whether we recognize it or not, average daily gain (ADG), feed efficiency and milk production will also decline during this time. A very high percentage of the herd will have diarrhea, but the number of animals that succumb to the disease is very low.”
Hanzlicek also points out the disease doesn’t usually affect breeding productivity because it is so mild and short lived.
Hanzlicek notes there are certain risk factors that promote the onset of winter bovine dysentery.
“Herds who have had the adult strain of coronavirus before, even if they are seeing it periodically, are more at risk for the disease. Age is also a risk factor, as it usually infects cattle two to six years old,” he says. “Some researchers have found a sudden drop in temperature can also bring it on.”
Other risk factors Hanzlicek mentions are confinement, poor ventilation and herds that are bovine viral diarrhea (BVD) positive.
“We also see winter bovine dysentery on operations that use their loaders to not only load feed but to push manure with the same bucket,” Hanzlicek states. “Sanitation is always important.”
According to Hanzlicek, there are no effective treatments for winter bovine dysentery.
“Like all viruses in bovine medicine, we don’t have any anti-virals,” says Hanzlicek. “The good news is it is self-limiting. It is a mild disease so within a few weeks the animals will have fully recovered.”
Hanzlicek encourages producers with infected herds to ensure their cattle have access to plenty of fresh water and feed.
“We know their intake will be down, but they will be dehydrated, and we want to make sure they have access to something they will actually want to eat, something that is palatable and fresh,” he says.
Hanzlicek notes there are a lot of neonatal coronavirus antibiotics on the market, but not many for older animals. However, he does point out there are a few older coronavirus vaccines, one is oral and the other is inter-nasal.
“These two have been shown to be effective to prevent the disease,” Hanzlicek says. “However, mass medication is not the answer for winter bovine dysentery, so I do not suggest going out and vaccinating the whole herd to prevent it. Producers who have had issues with this disease in the past should consult their veterinarians about a vaccination program.”
Although winter bovine dysentery is a mild disease, with little effect on productivity, Hanzlicek stresses the importance of making the distinction between dysentery and other afflictions in beef cattle that cause diarrhea.
“There are other things out there like salmonella, coccidia and occasionally, BVD, so I strongly recommend calling a vet and doing a diagnostics test to make sure we know what organism we are dealing with,” he says.
Hannah Bugas is the assistant editor for the Wyoming Livestock Roundup. Send comments on this article to firstname.lastname@example.org.